Apple initially planned for the watch to run 2.5 to 5 hours based on active use. It was also eyeing a goal of three days on standby mode and four days in sleep mode. But the wearable device may last only two to three days in either standby or low-power mode, according to 9to5Mac.

Battery life is critical to smartwatches since device owners expect such a device to last through the day. In addition, owners will want the ability to tap into its full array of apps and features without draining the battery too quickly. In October, Apple CEO Tim Cook said that he expects people to charge the watch on a daily basis. because they will be using it so frequently.

Still, 9to5MAc's report -- if accurate -- may not be so damning if people use the watch sporadically. The watch won't be on or active all the time. As a partner to the iPhone, it will spring to life only when you receive an incoming phone call, text message or alert. The watch's animated clock face will last for around three hours straight, but that's only when the watch is in use. When you're not using or checking the watch, the display shuts off, thereby preserving battery life. Also, the average person may use the watch as a fitness tracker only during a workout or only to occasionally check health stats.

However, Apple is a company known for perfectionism, so battery life has been a concern. That's reportedly one reason the company pushed back the launch of its smartwatch from late 2014 to early 2015. Apple continues to gauge the watch's performance with almost 3,000 units being tested under real-world conditions.